Despite the biological importance of mammalian meiosis, several of its significant features rema n largely unexplained. Recent discoveries by ourselves and others have shown that many of these features are controlled by the same protein, PRDM9. Our long-term objective is to determine how these controls are related, how they are achieved, and how PRDM9 fits into the larger network of proteins controlling meiosis progression. This will be greatly facilitated by the availability of multiple PRDM9 alleles in mice, each with its own regulatory specificities expressed in the most useful mammalian experimental model that we have. PRDM9 is an exceptional protein in the diversity of biological functions it carries out, in its unusual domain structure, and in its diverse molecular activities. The insights this study will provide extend beyond meiosis to major aspects of population genetics, as the location of hotspots determines patterns of inheritance; to genetic mapping studies identifying human disease genes; and to evolutionary biology, as allelic incompatibilities in PRDM9 can produce hybrid sterility. To address the relevant experimental questions, we have organized a coordinated effort among four projects representing diverse experimental approaches: genetics (Project A), protein chemistry (Project B), computational integration (Project 0), cell biology (Project D), and molecular biology (Projects A, B, C and D). Our Animal Resources Core will provide mice and new mutant strains. A Cell Biology Core will provide preparations of spermatocytes and assist in ChIP experiments. The Computational Core will perform data management and analysis. Our long-term objectives derive from the following overall program goals: a) Comprehensively define PRDM9's regulatory functions in recombination, transcription, and gametogenesis; b) Define the role of PRDM9 in regulation of meiosis by identifying and characterizing its interactions with genomic DNA, other meiotic proteins, and specialized meiotic structures; c) Define the overall role of PRDM9 in gametogenesis, hotspot activation, and transcription by using computational techniques to build an integrated model of its molecular functions; and d) Exploit the exceptional degree of variability in the Zn fingers (ZNF) of PRDM9 to clarify the complex nature of ZNF - DNA interactions, which are so ubiquitous in genomic regulation. Results of the program project will significantly increase the understanding of the mechanisms that regulate meiosis as well as their involvement in other important biological processes.